Stereotactic Access Devices And Methods

ABSTRACT

This invention is directed to devices and methods for stereotactic access, and particularly to a frameless stereotactic access device for accessing a body cavity and methods therefor. In general, a stereotactic device may include portions or features for fixing the device to a portion of a patient&#39;s body, such as, for example, a skull, such that the device may be generally spatially fixed in relation to the patient&#39;s body or part thereof. The stereotactic device may also generally include portions or features for guiding a medical device or other device at a particular trajectory in relation to the patient&#39;s body or part thereof.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of U.S. Provisional Application No.61/930,781 filed on Jan. 23, 2014. The entire disclosure of the aboveapplication is incorporated herein by reference.

FIELD

The present disclosure relates to devices and methods for stereotacticaccess, and particularly to a frameless stereotactic access device foraccessing a body cavity and methods therefor.

BACKGROUND

This section provides background information related to the presentdisclosure which is not necessarily prior art.

Stereotactic head frames have a long and proven history in neurosurgery.The two most commonly used are the Leksell (Elekta) and CRW (IntegraNeurosciences) frames. In these procedures, a frame is mounted to thehead by screwing pins directly against the patient's skull for fixationat four points. The head with attached frame are then imaged by CT orMRI to identify targets, either manually or more frequently withcomputerized software, in relation to the external frame. Since both theframe and target can be viewed on the images, the distance of the targetfrom given reference points on the frame can be measured in threecoordinates. Next in the OR, an arc apparatus is attached to the headframe and adjusted based on the previously measured coordinates anddesired trajectory. Once in position, a guide is used to drill a holealong a trajectory to the target. These head frames are associated withhigh accuracy (1-2 mm) for reaching target structures, much of which isachieved by having a permanent fixation between the skull and guidebeing used for creating the cranial access. Unfortunately, the frame iscumbersome, uncomfortable for patients, and time intensive.

Frameless stereotactic procedures rely on registration of the patient'sskull using anatomical landmarks, skin fiducial, or bone fiducials to apre-acquired MRI or CT scan. In the operating room the orientation offiducial markers or skin surfaces is registered using stereoscopiccameras on the navigation system to a volume of brain images. Onceregistration is completed, the navigation system can show therelationship of any registered surgical instruments to patient's brainanatomy. The two major manufacturers of these neuronavigation systemsare Medtronic and Brainlabs. Both companies offer accessories whichattach to the patients bed to allow twist drill access to a target alonga defined trajectory. A potential drawback to these accessories(Medtronic—Precision Aiming Device and Brainlab Varioguide) are thatneither is directly attached to the patient's head, and therefore anymovement of the drill may not be directly accompanied by a correspondingmovement of the head. Both systems may also require additional time andresource to set up in the operating room. Finally, because skinfiducials are movable in relation to the underlying skull, additionalerror may be realized from the registration alone.

SUMMARY

This section provides a general summary of the disclosure, and is not acomprehensive disclosure of its full scope or all of its features.

This invention is directed to devices and methods for stereotacticaccess, and particularly to a frameless stereotactic access device foraccessing a body cavity and methods therefor. In general, a stereotacticdevice may include portions or features for fixing the device to aportion of a patient's body, such as, for example, a skull, such thatthe device may be generally spatially fixed in relation to the patient'sbody or part thereof. The stereotactic device may also generally includeportions or features for guiding a medical device or other device at aparticular trajectory in relation to the patient's body or part thereof.

In one aspect, a stereotactic access device includes a plurality ofmounting arms which may further include mounting devices or featuressuch that, for example, the stereotactic access device may be mountedsecurely to a patient's body or part thereof. In some embodiments, themounting arms may generally be adapted to provide a stable mounting ofthe stereotactic access device to a patient's body or part thereof. Forexample, many body parts have curved or irregular surfaces such thatstable mounting may be desirable. In an exemplary embodiment, themounting arms may form at least a stable plane such that when themounting arms are attached to the patient's body, the stereotacticaccess device may generally be spatially stable and/or attachedsecurely. In one embodiment, the stereotactic access device may includethree mounting arms which may form a stable plane. The mounting arms mayalso be adapted to conform to the contours of a patient's body or partthereof, such as, for example, a skull. The mounting arms may further beadapted to contour, for example, such that there may be access spacebetween the stereotactic access device and the patient's body and/orportion thereof. This may be desirable, for example, to manipulate amedical device and/or other device between the stereotactic accessdevice and the patient's body and/or portion thereof.

In another aspect, a stereotactic access device includes a mountingand/or guiding feature such that a medical device and/or other devicemay be mounted to or guided to the stereotactic access device such that,for example, the device may be retained at a particular orientationand/or spatial relationship to the patient's body or part thereof. Insome embodiments, the mounting and/or guiding feature may include arotatable portion, such as an orbitally rotatable and/or swivelableportion, such that the orientation of the portion may be changed withrespect to the patient's body, a portion thereof, and/or the rest of thestereotactic access device. In an exemplary embodiment, the mountingand/or guiding feature may include, for example, a rotating sphere whichmay further include a guide channel to, for example, receive a medicaldevice and/or other device. The stereotactic access device may furtherinclude a locking and/or fixing feature for reversibly locking theorientation and/or position of the mounting and/or guiding featurerelative to the stereotactic access device. For example, at least onesecuring screw may be utilized to frictionally contact and/or at leastpartially screw into a mounting and/or guiding feature to lock itsposition and/or orientation. Also for example, at least two securingscrews may be utilized with mounting and/or guiding features havingmultiple degrees of freedom to aid in preventing loss of alignment andorientation, such as by each locking a particular axis of rotation.

In some embodiments, the mounting and/or guiding feature may include acentered channel, and in other embodiments, the mounting and/or guidingfeature may include an off-center channel and/or multiple channels suchthat a greater degree of variability in position and trajectory forguiding a medical device and/or other device through the stereotacticaccess device may be achieved from a single static mounting of thestereotactic access device onto a patient's body. This variability maybe desirable as unexpected and/or unplanned obstructions may be presentin a planned trajectory to a target and it may generally be desirable tomake small adjustments to the trajectory without having to repositionthe entire stereotactic access device which may be attached a patient'sbody.

In a further aspect, a stereotactic access device includes features foraiding in mounting, positioning and/or registering the position and/ororientation of the stereotactic access device, for example, in relationto the patient's body and/or portion thereof. In some embodiments, thestereotactic access device may include, for example, mounting hardwaresuch as, for example, screws, nails, bolts, pins, and/or any otherappropriate mounting hardware or combination thereof. For certaincurvatures and/or shapes of a body and/or portion thereof, spacersand/or other adjustment accessories, such as spacers between the end ofthe mounting arm(s) and the body, may be utilized such that a stableplane may be established with the stereotactic access device. Ingeneral, the mounting hardware may provide, for example, stable and/orsecure retention and/or fixation of the stereotactic access device to apatient's body and/or portion thereof, such as, for example, to a boneor soft tissue via, for example, mounting arms. In some embodiments, themounting hardware may also provide and/or act as, for example, fiducialmarkers for aiding in positioning and/or registering the position and/ororientation of the stereotactic access device, such as, for example,relative to the patient's body and/or portion thereof. For example, themounting hardware may be registered and/or imaged by a detectionmodality, such as, for example, magnetic resonance imaging (MRI), X-ray,computerized tomography (CT), ultrasound, and/or any other appropriatedetection modality or combination thereof.

In another aspect, a stereotactic access device is utilized in methodsfor accessing the interior of a patient's body at a particular locationand/or along a particular trajectory. In an exemplary embodiment, amethod for stereotactic access may include:

Step 1: After registration of the patient and navigation tools, astandard navigation wand may be used to determine and mark a rough entrypoint, and the patient may then be prepped. The navigation wand may thenbe inserted into the sphere of the stereotactic access device such thatthe surgeon may hold both devices, for example, with one hand.

Step 2: Using stereotactic navigation software, the surgeon may find thedesired entry point again and may then align the navigation wand withthe planned trajectory to a target. The surgeon may then slide thestereotactic access device down onto the patient's body and mountinghardware, such as, for example, three small titanium screws, may then besecured, for example, through the skin and into bone, such as, forexample, the skull. The wand may be used again to confirm thetrajectory, such as prior to locking the device in place.

Step 3: The surgeon may then remove the navigation wand and replace itwith, for example, one of several various sized drill adapters. A stabincision may also be made at the entry site under the stereotacticaccess device. A surgical drill may then be inserted along the lockedtrajectory and a twist drill hole may be created through, for example, abone such as the skull.

Step 4: The drill adapter may then be retracted to optionally allow, forexample, a bone screw or anchor to be placed under the stereotacticaccess device. The drill adapter may be made to fit into the bone screwor anchor's proximal end such that the threads of the screw may fallinto the hole created in step 3. A biopsy probe may also be passeddirectly through an appropriate adapter, for example, such as with itsown thumb screw, and may be used to acquire, for example, tissuesamples.

Step 5: For placement of probes or electrodes, the surgeon may securethe bone screw by securing it in, for example, the previously drilledhole.

Step 6: The stereotactic access device may be removed, for example, byunscrewing the three screws, and if any stab incisions were created,they may be closed using a single staple or suture. A Touhy-Borstadapter may also be threaded onto the proximal female luer of the bonescrew, which may allow applicators to pass through while ensuring asterile field.

In some embodiments, the stereotactic access device may also be left inplace after a hole is drilled. For example, a bone screw may connect tothe stereotactic access device such that a continuous sealed channel maybe established from the stereotactic access device through the bonescrew and into the body. A sealing cap and/or other sealing componentmay also be included to close off the introducing end of thestereotactic access device.

In other embodiments, the stereotactic access device may be left inplace and an introducer may be inserted into the channel of thestereotactic access device and into the drilled hole in the body. Theend of the introducer may further include a cap and/or a seal such thatthe channel may be kept sterile.

In some aspects, the stereotactic access device may be desirable as itmay generally be utilized with existing and/or standard practicenavigation devices, probes and/or systems, and may thus be adaptable toa diverse number of medical practices with very little additionaltraining and/or the need for specialized equipment. For example, thestereotactic access device may generally be compatible and/or becompatible via adapters to receive a standard navigation probe or wand,treatment devices, drills and/or other equipment used in stereotacticsurgery. Further, use of the stereotactic access device may generally beintuitive and aid in surgical usage with a minimal number of movingparts and/or components such that, for example, users may use thestereotactic access device with minimal difficulty, while still beinghighly versatile in application due to a universal use design.

In an exemplary aspect, a stereotactic access device may be a multiplepart device which may, for example, be utilized to aid in maintaining asterile field for use in stereotactic surgery while establishing atrajectory to a target inside a patient's body. In one exemplaryembodiment, the stereotactic access device may include a frame portionand an attachable/detachable cover portion, such that the frame portionmay be secured to the patient's body, while the cover portion may beattached and removed from the frame portion. This may be desirable asthe stereotactic procedures may take place partially in a sterileenvironment, such as an operating room, and partially in an unsterileenvironment, such as a medical imaging room or suite. Thus, prior toperforming a stereotactic surgical procedure, the stereotactic accessdevice may be oriented and attached to a patient's body in an unsterileenvironment using the frame portion and an unsterile cover portion,followed by removal of the unsterile cover portion and replacement witha sterile cover portion for use in a sterile environment.

In some embodiments, the cover portion(s) may also include additionalfiducial markers, as discussed above, such that they may aid inproviding additional registration information and may also be used toverify proper alignment and attachment of the cover portion(s) to theframe portion as they are removable.

In some embodiments, the cover portion(s) and the frame portion mayinclude features for reversible secure attachment to each other, whichmay include, but are not limited to, screws, nuts, bolts, nails,magnets, reversible adhesives, locking levers, and/or any otherappropriate reversible secure attachments.

Further areas of applicability will become apparent from the descriptionprovided herein. The description and specific examples in this summaryare intended for purposes of illustration only and are not intended tolimit the scope of the present disclosure.

BRIEF DESCRIPTION OF THE DRAWINGS

The drawings described herein are for illustrative purposes only ofselected embodiments and not all possible implementations, and are notintended to limit the scope of the present disclosure.

FIGS. 1, 1A, 1B and 1C illustrate a stereotactic access device in someembodiments of the present invention;

FIGS. 2-1, 2-2, 2-3, 2-4, 2-5 and 2-6 illustrate the steps of a methodof stereotactic access to a patient's body in some embodiments of thepresent invention;

FIGS. 3 and 3A illustrate an example of a frameless stereotactic accessdevice;

FIGS. 3B and 3C illustrate an example of a bone anchor for use with aframeless stereotactic access device;

FIGS. 4, 4A and 4B illustrate a frameless stereotactic access devicewith a sealed device introducer;

FIGS. 5, 5A and 5B illustrate a frameless stereotactic access devicewith a cover portion and a frame portion;

FIG. 5′ illustrates a frameless stereotactic access device with a coverportion and a frame portion with a single securing screw for themounting ball;

FIGS. 5C and 5D illustrate the frame portion of a frameless stereotacticaccess device;

FIGS. 5E and 5F illustrate locking levers for securing a cover portionto a frame portion;

FIG. 6 shows a frameless stereotactic access device attached to apatient's body;

FIG. 6A shows a frameless stereotactic access device with reversiblyattachable cover portion and frame portion;

FIGS. 7, 7A, 8, 8A, 8 B, 8C, 8D, and 8E illustrate an example ofaligning and securing a frameless stereotactic access device to apatient's body; and

FIGS. 9, 9A, 9B and 9C illustrate examples of different channels andapertures in a mounting ball.

Corresponding reference numerals indicate corresponding parts throughoutthe several views of the drawings.

DETAILED DESCRIPTION

Example embodiments will now be described more fully with reference tothe accompanying drawings.

The detailed description set forth below is intended as a description ofthe presently exemplified devices, methods and materials provided inaccordance with aspects of the present invention, and it is not intendedto represent the only forms in which the present invention may bepracticed or utilized. It is to be understood, however, that the same orequivalent functions and components may be accomplished by differentembodiments that are also intended to be encompassed within the spiritand scope of the invention.

Unless defined otherwise, all technical and scientific terms used hereinhave the same meaning as commonly understood to one of ordinary skill inthe art to which this invention belongs. Although any methods, devicesand materials similar or equivalent to those described herein can beused in the practice or testing of the invention, the exemplifiedmethods, devices and materials are now described.

This invention is directed to devices and methods for stereotacticaccess, and particularly to a frameless stereotactic access device foraccessing a body cavity and methods therefor. In general, a stereotacticdevice may include portions or features for fixing the device to aportion of a patient's body, such as, for example, a skull, such thatthe device may be generally spatially fixed in relation to the patient'sbody or part thereof. The stereotactic device may also generally includeportions or features for guiding a medical device or other device at aparticular trajectory in relation to the patient's body or part thereof.

In one aspect, a stereotactic access device includes a plurality ofmounting arms which may further include mounting devices or featuressuch that, for example, the stereotactic access device may be mountedsecurely to a patient's body or part thereof. In some embodiments, themounting arms may generally be adapted to provide a stable mounting ofthe stereotactic access device to a patient's body or part thereof. Forexample, many body parts have curved or irregular surfaces such thatstable mounting may be desirable. In an exemplary embodiment, themounting arms may form at least a stable plane such that when themounting arms are attached to the patient's body, the stereotacticaccess device may generally be spatially stable and/or attachedsecurely. In one embodiment, the stereotactic access device may includethree mounting arms which may form a stable plane. The mounting arms mayalso be adapted to conform to the contours of a patient's body or partthereof, such as, for example, a skull. The mounting arms may further beadapted to contour, for example, such that there may be access spacebetween the stereotactic access device and the patient's body and/orportion thereof. This may be desirable, for example, to manipulate amedical device and/or other device between the stereotactic accessdevice and the patient's body and/or portion thereof.

FIG. 1 illustrates an example of an embodiment of a stereotactic accessdevice 100. In some embodiments, such as illustrated, the stereotacticaccess device 100 may generally be a tripod and may include mountingarms 102, such as the three illustrated, which may provide a stableplanar platform when mounted to a patient's body. The mounting arms 102may also generally form a space 106 between the stereotactic accessdevice 100 and a patient's body. This may be desirable such that thearea may be freely accessed when the stereotactic access device 100 isin place on the patient's body.

In another aspect, a stereotactic access device includes a mountingand/or guiding feature such that a medical device and/or other devicemay be mounted to or guided to the stereotactic access device such that,for example, the device may be retained at a particular orientationand/or spatial relationship to the patient's body or part thereof. Insome embodiments, the mounting and/or guiding feature may include arotatable portion such that the orientation of the portion may bechanged with respect to the patient's body, a portion thereof, and/orthe rest of the stereotactic access device. In an exemplary embodiment,the mounting and/or guiding feature may include, for example, a rotatingsphere which may further include a guide channel to, for example,receive a medical device and/or other device. Various adapters, shimsand/or other devices may be utilized to accommodate different sizedand/or shaped devices securely in the guide channel.

In FIG. 1, the stereotactic access device 100 may include a mountingball 110, which may be retained in track 108. The mounting ball 110 maygenerally rotate in the track 108 such that the guide channel 111 may bealigned at the appropriate angle, such as illustrated in FIG. 1A. Themounting ball 100 may thus retain another device, such as, for example,a navigation wand 200, relative to the patient's body 90, such asillustrated in FIG. 1A. The mounting ball 110 may also include asecuring part or feature, such as, for example, a securing screw, suchthat the mounting ball 110 may be locked in a particular orientation,such as with the thumbscrew 112 illustrated in FIGS. 1B and 1C. Thethumbscrew 112 can include a distal pointed tip that enables thethumbscrew 112 to bite into the ball 110 in order to securely hold theball 110 in place. For example, the tip of the thumbscrew 112 can beconfigured as a self-tapping screw tip.

The stereotactic access device may further include a locking and/orfixing feature for reversibly locking the orientation and/or position ofthe mounting and/or guiding feature relative to the stereotactic accessdevice, as shown with the thumbscrew 112 in FIGS. 1B and 1C, and withthe screws 112 in FIGS. 5, 5A and 5B. For example, at least one securingscrew may be utilized to frictionally contact and/or at least partiallyscrew into a mounting and/or guiding feature to lock its position and/ororientation. Also for example, at least two securing screws may beutilized with mounting and/or guiding features having multiple degreesof freedom to aid in preventing loss of alignment and orientation, suchas by each locking a particular axis of rotation, as illustrated withthe two screws 112 in FIGS. 5, 5A and 5B.

The mounting and/or guiding feature may include a variety of channelsand/or other apertures, examples of which are illustrated in FIGS. 9,9A, 9B and 9C. In some embodiments, the mounting and/or guiding feature,such as the sphere 110 as illustrated, may include a centered channel111, as in FIG. 9A, and in other embodiments, the mounting and/orguiding feature may include an off-center channel and/or multiplechannels such that a greater degree of variability in position andtrajectory for guiding a medical device and/or other device through thestereotactic access device may be achieved from a single static mountingof the stereotactic access device onto a patient's body. FIG. 9illustrates a cross-shaped slot aperture 111′ with multiple accesspositions. FIG. 9B illustrates an off center channel 111. FIG. 9Cillustrates multiple channels 111 a and 111 b. Various other channelsand apertures may be utilized depending on a particular application ordevice being used.

This variability may be desirable as unexpected and/or unplannedobstructions may be present in a planned trajectory to a target and itmay generally be desirable to make small adjustments to the trajectorywithout having to reposition the entire stereotactic access device whichmay be attached a patient's body.

In a further aspect, a stereotactic access device includes features foraiding in mounting, positioning and/or registering the position and/ororientation of the stereotactic access device, for example, in relationto the patient's body and/or portion thereof. In some embodiments, thestereotactic access device may include, for example, mounting hardwaresuch as, for example, screws, nails, bolts, pins, and/or any otherappropriate mounting hardware or combination thereof. For certaincurvatures and/or shapes of a body and/or portion thereof, spacersand/or other adjustment accessories, such as spacers between the end ofthe mounting arm(s) and the body, may be utilized such that a stableplane may be established with the stereotactic access device. Ingeneral, the mounting hardware may provide, for example, stable and/orsecure retention and/or fixation of the stereotactic access device to apatient's body and/or portion thereof, such as, for example, to a boneor soft tissue via, for example, mounting arms. In some embodiments, themounting hardware may also provide and/or act as, for example, fiducialmarkers for aiding in positioning and/or registering the position and/ororientation of the stereotactic access device, such as, for example,relative to the patient's body and/or portion thereof. For example, themounting hardware may be registered and/or imaged by a detectionmodality, such as, for example, magnetic resonance imaging (MRI), X-ray,computerized tomography (CT), ultrasound, and/or any other appropriatedetection modality or combination thereof.

As illustrated in FIG. 1, the stereotactic access device 100 mayinclude, for example, screws 103, which may be mounted at the ends 104of the mounting arms 102. The screws 103 may be, for example,self-tapping such that they may, for example, thread themselves into asurface, such as the patient's body. The screws 103 may also act asfiducials, as discussed above. For certain curvatures of the body and/orother situations requiring adjustment of the apparent dimensions of themounting arms 102, spacers may be included, such as, for example, aboutthe screws 103 between the end of the mounting arms 102 and the body,such that they may, for further example, effectively lengthen themounting arms 102.

In another aspect, a stereotactic access device is utilized in methodsfor accessing the interior of a patient's body at a particular locationand/or along a particular trajectory. In an exemplary embodiment, amethod for stereotactic access may include:

Step 1: As illustrated in FIG. 2-1, after registration of the patientand navigation tools, a standard navigation wand 200 may be used todetermine and mark a rough entry point 92 on the patient's body 90, andthe patient may then be prepped. The navigation wand 200 may then beinserted into the sphere of the stereotactic access device 100 such thatthe surgeon may hold both devices, for example, with one hand. Examplesof a navigation system and registration are set forth in U.S. Pat. Nos.6,491,699 and 7,313,430, which are hereby incorporated by referenceherein.

Step 2: As illustrated in FIG. 2-2, using stereotactic navigationsoftware, the surgeon may find the desired entry point 92 again and maythen align the navigation wand 200 with the planned trajectory to atarget. The surgeon may then slide the stereotactic access device 100down onto the patient's body 90 and mounting hardware, such as, forexample, three small titanium screws, may then be secured, for example,through the skin and into bone, such as, for example, the skull. Thenavigation wand 200 may be used again to confirm the trajectory, such asprior to locking the stereotactic access device 100 in place.

Step 3: As illustrated in FIG. 2-3, the surgeon may then remove thenavigation wand 200 and replace it with, for example, one of severalvarious sized drill adapters 310. A stab incision may also be made atthe entry site 92 under the stereotactic access device 100. A surgicaldrill 300 may then be inserted along the locked trajectory and a twistdrill hole may be created through, for example, a bone such as theskull, at the entry site 92.

Step 4: As illustrated in FIG. 2-4, the drill adapter 310 may then beretracted to optionally allow, for example, a bone screw or anchor 400to be placed under the stereotactic access device 100. The drill adapter310 may be made to fit into the bone screw or anchor's 400 proximal endsuch that the threads of the screw 400 may fall into the hole created instep 3 at the entry site 92. A biopsy probe may also be passed directlythrough an appropriate adapter, for example, such as with its own thumbscrew, and may be used to acquire, for example, tissue samples.

Step 5: As illustrated in FIG. 2-5, for placement of probes orelectrodes, the surgeon may secure the bone screw 400 by securing it in,for example, the previously drilled hole at the entry site 92.

Step 6: As illustrated in FIG. 2-6, the stereotactic access device 100may be removed, for example, by unscrewing the three screws, and if anystab incisions were created, they may be closed using a single staple orsuture. A Touhy-Borst adapter 410 may also be threaded onto the proximalfemale luer of the bone screw 400, which may allow applicators to passthrough while ensuring a sterile field.

In some embodiments, the stereotactic access device 100 may also be leftin place after a hole at entry site 92 is drilled. For example, a bonescrew 400 may connect to the stereotactic access device 100 such that acontinuous sealed channel may be established from the stereotacticaccess device 100 through the bone screw 400 and into the body 90. Asealing cap and/or other sealing component may also be included to closeoff the introducing end of the stereotactic access device 100.

In other embodiments, such as illustrated in FIGS. 4, 4A and 4B, thestereotactic access device 100 may be left in place and an introducer400′ may be inserted into the channel 111 of the stereotactic accessdevice 100 and into the drilled hole at the entry site 92 in the body90. The end of the introducer 400′ may further include a cap and/or aseal, such as the sealing cap 410 as illustrated in FIG. 4, such thatthe channel 402 may be kept sterile. The insertable portion 404 may beretained in the guide channel 111. The insertable end 405 may further bethreaded to engage the drilled hole at the entry site 92. A device 500,such as a laser probe and/or other type of medical device, may then beinserted into the channel 402 through the introducer 400′ and into thebody through the entry site 92, as illustrated in FIG. 4B.

In an exemplary aspect, a stereotactic access device may be a multiplepart device which may, for example, be utilized to aid in maintaining asterile field for use in stereotactic surgery while establishing atrajectory to a target inside a patient's body. In one exemplaryembodiment, as illustrated in FIGS. 5, 5A and 5B, the stereotacticaccess device 100′ may include a frame portion 120 and anattachable/detachable cover portion 102′. As with the stereotacticaccess device 100, above, the stereotactic access device 100′ maygenerally form a tripod to accommodate curved and/or uneven surfaces, asexplained above, with ends 104 of the cover portion 102′ and thecorresponding ends 124 of the frame portion 120. The frame portion 120may generally form an opening 125, as shown in FIGS. 5C and 5D, whichmay be covered by the cover portion 102′ when it is attached. Ingeneral, the frame portion 120 may be secured to the patient's body 90,such as on a curved and/or other non-flat surface 92, as shown in FIG.6, while the cover portion 102′ may be attached and removed from theframe portion 120, as shown in FIG. 6A, such that the stereotacticaccess device 100′ as a whole may be secured to the patient's body 90.This may be desirable as the stereotactic procedures may take placepartially in a sterile environment, such as an operating room, andpartially in an unsterile environment, such as a medical imaging room orsuite. Thus, prior to performing a stereotactic surgical procedure, thestereotactic access device 100′ may be oriented and attached to apatient's body 90 in an unsterile environment using the frame portion120 and an unsterile cover portion 102′, followed by removal of theunsterile cover portion 102′ and replacement with a sterile coverportion 102′ for use in a sterile environment. A kit may be providedwith multiple cover portions 102′ for use in this way. The coverportions 102′ may further be visually and/or materially different foreach purpose. For example, a non-sterile cover portion 102′ may notrequire a material that may withstand significant sterilization.

In some embodiments, the cover portion 102′, the frame portion 120,and/or the entire stereotactic access device 100 or 100′, or componentsor portions thereof, may be translucent or transparent to aid in, forexample, visualizing the position, orientation of the stereotacticaccess device 100 or 100′ and/or the patient's body 90 underneath.

In some embodiments, as illustrated in FIGS. 5, 5A, 5B, 5C and 5D,mounting hardware, such as the screws 103 shown, may insert into theframe portion 120 at mounting holes 123 at each end 124 to secure theframe portion 120 to a patient's body 90. Further, the cover portion102′ may include apertures 104 a at each end 104 to provide access tothe screws 103 through the cover portion 102′ while it is attached tothe frame portion 120. This may be utilized, for example, to manipulatethe screws 103 while the cover portion 102′ is attached to the frameportion 120. In general, the mounting hardware, such as the screws 103,may only secure the frame portion 120 to the patient's body 90, and notsecure the cover portion 102′ to the patient's body 90 directly suchthat the cover portion 102′ may be freely removed and/or attached fromthe frame portion 120 without disturbing the secured attachment of theframe portion 120 to the patient's body 90.

In some embodiments, the cover portion(s) 102′ may also includeadditional fiducial markers, such as shown with fiducial markers 105, asdiscussed above, such that they may aid in providing additionalregistration information and may also be used to verify proper alignmentand attachment of the cover portion(s) 102′ to the frame portion 120 asthey are removable.

FIG. 5′ further illustrates an embodiment of a stereotactic accessdevice 100″ which may also include a cover portion 102′ and a frameportion 120, as above with stereotactic access device 100′, and mayemploy a single securing screw 112 for the mounting ball 110.

In some embodiments, the cover portion(s) 102′ and the frame portion 120may include features for reversible secure attachment to each other,which may include, but are not limited to, screws, nuts, bolts, nails,magnets, reversible adhesives, locking levers, and/or any otherappropriate reversible secure attachments.

FIGS. 5, 5A, 5B, 5C and 5D illustrate a pair of locking levers 112 whichmay be used to reversibly secure the cover portion 102′ to the frameportion 120. For example and as illustrated, the locking levers 112 maybe turned from locked to unlocked (and vice versa) which may manipulatethe orientation of locking portion 122 a which may secure to the frameportion 120 at locking apertures 121. For example, as shown in FIGS. 5Eand 5F, the locking levers 112 may include an extension 112 a which mayfit through a corresponding shaped portion 121 a of aperture 121 of theframe portion 120. Thus, as in FIG. 5E, when the extension 112 a isaligned with the portion 121 a, the cover 102′ may be unlocked from theframe portion 120 and removed. The locking lever 112 may be rotated suchthat the portion 121 a is not aligned with the extension 112 a which mayabut against the portion 121 b to lock the cover portion 102′ to theframe portion 120. The cover portion 102′ may further include indicators112 b for indicating locked vs. unlocked orientations of the lockinglevers 112. In general, multiple locking features may be used to aid inensuring the proper orientation of the cover portion 102′ relative tothe frame portion 120, as shown with the two locking levers 112 andcorresponding features illustrated in FIGS. 5, 5A, 5B, 5C and 5D.

Example of Construction of a Frameless Stereotratic Cranial Access Guide

In an example of a stereotactic access device, a frameless stereotacticcranial access guide (FIGS. 3, 3A, 3B and 3C) includes 2 parts—Tripod100 and a bone screw 400. The tripod 100 (measuring for example 2.5″ indiameter and 1.25″ in height) may hold several adapters for variousnavigation wands, drills, and bone screws 400 (measuring for example1.5″ in diameter). Wherever the tripod 100 is located on the cranium,the feet may be seated to allow all three screws to have a solid hold tothe skull, due to the planar tripod body design. Space is providedbetween the patient's skull and the base of the sphere 110 to allowaccess to the incision/entry point. The sphere 110 press fits into thebody of the tripod 100 and swivels in all directions. The through hole111 in the sphere 110 may fit various adapters for several parts of theprocedure. The thumbscrew 112 is used to tighten and secure the sphere110 in a particular orientation once the desired trajectory is achieved.Three guide screws 103 are located on the tips 102 of the tripod 100 andmay secure to the skull and anchor the guide in its position over theskull, such as, for example, over the entry point.

Example of Orienting and Securing a Stereotactic Access Device to aPatient's Body

As illustrated in FIGS. 7 and 7A, a navigation wand 200 may be insertedinto the channel 111 of a stereotactic access device 100′ and slid down.

As illustrated in FIG. 8, the tip portion 202 of the navigation wand 200may be contacted with the patient's body 90 at an entry point. Thenavigation wand 200 may be oriented along a proper trajectory usingnavigation software and/or imaging.

The stereotactic access device 100′ may then be slid down along the tipportion 202 to contact the patient's body 90, as shown in FIG. 8A. Thestereotactic access device 100′ may be rotated about the navigation wand200, to, for example, ensure the screws 103 are located at safe entrylocations on the patient's body 90 and to ensure that all features ofthe stereotactic access device 100′ are accessible, as illustrated inFIG. 8B.

The stereotactic access device 100′ may then be secured to the patient'sbody 90, such as with a screw driver 80 as illustrated in FIGS. 8C, 8Dand 8E. The alignment and position of the stereotactic access device100′ may be verified after securing each screw 103. The screws 103 maybe secured until the stereotactic access device 100′ is sufficientlysecure and the attachment to the patient's body 90 is stable and/orrigid.

The stereotactic access device 100′ may then be imaged and/or scanned toregister its position and alignment relative to the patient's body 90.To move into a sterile environment, the non-sterile cover portion 102′may be removed and the frame portion 120 may be sterilized. A sterilecover portion 102′ may then be attached to the frame portion in the sameorientation as the non-sterile cover portion 102′ and verified forproper alignment and/or position.

The foregoing description of the embodiments has been provided forpurposes of illustration and description. It is not intended to beexhaustive or to limit the disclosure. Individual elements or featuresof a particular embodiment are generally not limited to that particularembodiment, but, where applicable, are interchangeable and can be usedin a selected embodiment, even if not specifically shown or described.The same may also be varied in many ways. Such variations are not to beregarded as a departure from the disclosure, and all such modificationsare intended to be included within the scope of the disclosure.

What is claimed is:
 1. A stereotactic access device comprising: a framebody having an opening therethrough and plurality of mounting arms, eachof said arms mounting a securing device at an end; a cover body beingreversibly attachable to said frame body, said cover body covering saidopening in said frame body when attached; and a mounting guide having aguide channel, said mounting guide being retained in said cover body;wherein said plurality of mounting arms forms a stable planar platformwith a space underneath said frame body which accommodates curvature ofa surface.
 2. The stereotactic access device of claim 1, wherein saidplurality of mounting arms comprise three arms.
 3. The stereotacticaccess device of claim 1, wherein said securing device comprises aself-tapping screw.
 4. The stereotactic access device of claim 3,wherein said self-tapping screw comprises a registerable fiducial. 5.The stereotactic access device of claim 2, wherein said three arms forma tripod.
 6. The stereotactic access device of claim 1, wherein saidmounting guide comprises a mounting ball.
 7. The stereotactic accessdevice of claim 6, further comprising at least one locking screw adaptedto reversibly lock said mounting ball in an orientation relative to saidcover body.
 8. The stereotactic access device of claim 1, furthercomprising spacers at said ends of said arms.
 9. A method forstereotactic access to a patient's body comprising: registering apatient's body and at least one navigation tool in a space utilizing adetection modality; inserting said navigation tool in a guide channel ofa stereotactic access device having a plurality of mounting arms, aplurality of securing screws and at least one locking screw; aligningsaid navigation tool relative to said patient's body along a trajectorytoward a target; sliding said stereotactic access device along saidtrajectory toward said patient's body; securing said stereotactic accessdevice to said patient's body utilizing said securing screws; removingsaid navigation tool; removing a cover portion of said stereotacticaccess device while leaving a frame portion attached to said patient'sbody; sterilizing said frame portion and at least a portion of saidpatient's body adjacent to said frame portion; attaching a sterile coverportion to said frame portion; inserting a drill through said guidechannel; aligning said drill to said trajectory and locking said guidechannel in place utilizing said at least one locking screw; andaccessing said patient's body by drilling along said trajectory throughsaid guide channel to form an access channel in said patient's body. 10.The method of claim 9, further comprising placing a bone screw in saidaccess channel.
 11. The method of claim 9, further comprising utilizingnavigation software to align said navigation tool.
 12. The method ofclaim 9, wherein said access channel is through a skull.
 13. The methodof claim 9, further comprising inserting an adapter in said guidechannel for said drill.
 14. The method of claim 10, further comprisingremoving said stereotactic access device after placing said bone screw.15. The method of claim 9, further comprising placing an introducerhaving a through-channel through said guide channel and into said accesschannel.
 16. A system for stereotactic access to a body comprising: astereotactic access device comprising: a frame body having an openingtherethrough and a plurality of mounting arms, each of said armsmounting a securing device at an end; a cover body being reversiblyattachable to said frame body, said cover body covering said opening insaid frame body when attached; and a mounting guide having a guidechannel, said mounting guide being retained in said body; wherein saidplurality of mounting arms forms a stable planar platform with an accessspace; and a bone screw having a threaded portion and a channel.
 17. Thesystem of claim 16, wherein said bone screw comprises an introduceradapted to be received in and through said guide channel.
 18. The systemof claim 17, further comprising a sealing cap on said introducer. 19.The system of claim 16, wherein said mounting guide comprises a mountingball.
 20. The system of claim 19, further comprising at least onelocking screw adapted to reversibly lock said mounting ball in anorientation relative to said body.